This study is designed to determine the safety and tolerability, and identify the maximum tolerated dose of CCI-779, given intravenously once daily for five days, every two weeks, in patients who have advanced solid tumors. Secondary objectives are to determine the preliminary pharmacokinetics of CCI-779 on this schedule and to obtain information on the antitumor acitivity of CCI-779. Eleven patients have been treated thus far, including three from Mayo Clinic. Two Mayo Clinic patients have completed therapy. The maximum tolerated dose has not yet been achieved. Dose escalation will continue. Following completion of the phase I trial, phase II studies will begin.